Addressing the UN in New York, Mr Brown called for urgent action to avert the "greatest humanitarian disaster the world faces today".

In his speech, Mr Brown called for a "coalition of justice", in the spirit of John F Kennedy's peace corps.

Mr Brown secured US support for the resolution earlier this week and China and Russia agreed to back the proposal in the face of the prime minister's argument.

Resolution 1769 invokes chapter seven of the UN Charter, which allows the UN to authorise force to protect civilians from attack, as well as in self-defence and to ensure the free movement of humanitarian workers.

The final resolution was weakened from Mr Brown's first draft, removing the right of troops to seize weapons.

It also omits references to further sanctions, although Mr Brown said he would continue to push for these as an option.

He said: "If anything blocks progress and the killings continue, I and others will redouble our efforts to impose further sanctions.

"The plan for Darfur from now on is to achieve a cease-fire, including an end to aerial bombings of civilians; drive forward peace talks ... and, as peace is established, offer to begin to invest in recovery and reconstruction."

UN secretary-general Ban Ki-moon said the resolution was "historic" and called on member states to provide "capable" troops swiftly.

UN members will finalise their commitment within 90 days and Sudan has already agreed to the force.

The new force will be called UNAMID, or the UN-African Union Mission in Darfur. Troops will be largely drawn from African nations, mainly Rwanda and Nigeria.

It will comprise of 19,555 soldiers and 6,432 civilian police drawn from around the globe, and will replace the 7,000 African Union troops already in place in Darfur.

The UK will provide mainly financial support, contributing up to £100 million. The UN estimates the total cost of the mission could be more than £2 billion in the first year.

More than 2.1 million people have already been displaced into camps and at least 200,000 have died in the past four years.